Using identifier mapping to resolve access point identifier ambiguity

ABSTRACT

Ambiguity (e.g., confusion) associated with access point identifiers may be resolved by querying candidate target access points and/or by using historical records indicative of one or more access points that the access point has previously accessed. For example, messages may be sent to access points that are assigned the same identifier to cause the access points to monitor for a signal from an access terminal that received the identifier from a target access point. The target access point may then be identified based on any responses that indicate that a signal was received from the access terminal In some aspects the access points subject to being queried may be selected using a tiered priority. In addition, it may be determined based on prior handoffs of a given access terminal that when that access terminal reports a given identifier, the access terminal usually ends up being handed-off to a particular access point. Accordingly, a mapping may be maintained for that access terminal that maps the identifier to that access point so that the mapping may be used to resolve any future confusion associated with the use of that identifier by that access terminal.

CLAIM OF PRIORITY

This application claims the benefit of and priority to commonly ownedU.S. Provisional Patent Application No. 61/098,203, filed Sep. 18, 2008,and assigned Attorney Docket No. 082761P1, and U.S. Provisional PatentApplication No. 61/158,536, filed Mar. 9, 2009, and assigned AttorneyDocket No. 091570P1, the disclosure of each of which is herebyincorporated by reference herein.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to concurrently filed and commonly ownedU.S. patent application Ser. No. ______, entitled “USING SIGNALMONITORING TO RESOLVE ACCESS POINT IDENTIFIER AMBIGUITY,” and assignedAttorney Docket No. 082761U1, the disclosure of which is herebyincorporated by reference herein.

BACKGROUND

1. Field

This application relates generally to communication and morespecifically, but not exclusively, to techniques for resolving ambiguityassociated with access point identifiers.

2. Introduction

Wireless communication systems are widely deployed to provide varioustypes of communication to multiple users. For example, voice, data,multimedia services, etc., may be provided to users' access terminals(e.g., cell phones). As the demand for high-rate and multimedia dataservices rapidly grows, there lies a challenge to implement efficientand robust communication systems with enhanced performance.

To supplement conventional mobile phone network access points (e.g.,macro base stations), small-coverage access points may be deployed toprovide more robust indoor wireless coverage to access terminals. Suchsmall-coverage access points are generally known as access point basestations, Home NodeBs, Home eNodeBs, femto access points, or femtocells. Typically, such small-coverage access points are connected to theInternet and the mobile operator's network via a DSL router or a cablemodem (e.g., when installed in a user's home).

In practice, a relatively large number of small-coverage access pointsmay be deployed in a given area (e.g., within the coverage area of agiven macro cell). Consequently, several of these access points may beassigned the same identifier since the number of available identifiersis typically limited (e.g., physical layer identifiers may be only 10bits long). As a result, confusion may exist as to which access point(e.g., handover target) is being referenced when an access terminal inthe network reports to its serving access point (e.g., handover source)that a signal has been received from an access point having a givenidentifier. Thus, there is a need for effective techniques foridentifying access points so that other nodes in the network mayefficiently communicate with the access points.

SUMMARY

A summary of sample aspects of the disclosure follows. It should beunderstood that any reference to the term aspects herein may refer toone or more aspects of the disclosure.

The disclosure relates in some aspects to resolving ambiguity (e.g.,confusion) associated with access point identifiers. For example, whenan access terminal acquires a signal comprising an identifier of theaccess point that transmitted the signal and it is determined that theaccess terminal should be handed-over to that access point, confusionmay arise as to the precise identity of the access point identified bythat identifier. Various techniques are described herein for resolvingambiguities such as this.

The disclosure relates in some aspects to sending a message to one ormore access points that are assigned an identifier that is subject toconfusion, whereby each message requests a given access point to monitorfor a signal from the access terminal that reported the identifier. Thetarget access point may then be identified based on any responses thatindicate that a signal was received from the access terminal Forexample, if only one response is received, it may be assumed that theaccess point that sent the response is the target access point.Conversely, if more than one response is received, the access point thatreceived the signal having the highest received signal strength may beidentified as the target access point.

In some cases a tiered target selection scheme may be employed. Forexample, initially, a request may be sent to each access pointassociated with a first priority tier (e.g., home femto nodes of theaccess terminal to be handed-over). If the target access point cannot beidentified from the response(s) from the first tier access point(s), arequest may be sent to each access point associated with a secondpriority tier (e.g., access points that the access terminal haspreviously accessed). If the target access point cannot be identifiedfrom the response(s) from the second tier access point(s), a request maybe sent to each access point associated with a third priority tier, andso on. In addition, different algorithms may be employed at differenttiers. For example, one tier may involve making a decision based on therelative received signal strengths included with the responses, whileanother tier may involve making a decision based on a comparison of themacro neighbor list of the access terminal with the macro neighbor listsof the responding access points.

The disclosure relates in some aspects to resolving identifier confusionbased on historical records relating to which access points an accessterminal has previously accessed. For example, it may be determinedbased on prior handoffs of a given access terminal that when that accessterminal reports a given identifier, the access terminal usually (oralways) ends up being handed-off to a particular access point (or anyone of a limited set of access points). Accordingly, a mapping may bemade for that access terminal that maps the identifier to one or moreaccess points. Thus, if that identifier is subsequently received fromthat access terminal, the mapping may be used to identify which accesspoint(s) should be prepared for handover of the access terminal.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other sample aspects of the disclosure will be described inthe detailed description and the appended claims that follow, and in theaccompanying drawings, wherein:

FIG. 1 is a simplified block diagram of several sample aspects of acommunication system;

FIG. 2 is a flowchart illustrating several sample aspects of handoveroperations;

FIGS. 3A and 3B are a flowchart illustrating several sample aspects ofhandover operations;

FIG. 4A is a flowchart illustrating several sample aspects of operationsthat may be performed to maintain a historical use database and providetiered confusion resolution;

FIG. 4B is a simplified diagram illustrating a sample databasestructure;

FIG. 5 is a simplified block diagram of several sample aspects ofcomponents that may be employed in communication nodes;

FIG. 6 is a simplified call flow diagram of a sample handover procedure;

FIG. 7 is a flowchart illustrating several sample aspects of operationsfor performing a handover while resolving confusion through the use ofaccess terminal-specific mapping;

FIGS. 8A, 8B, and 8C are flowcharts illustrating several sample aspectsof operations that may be performed in conjunction with determiningaccess terminal-specific mapping;

FIG. 9 is a flowchart illustrating several sample aspects of operationsfor performing a handover while resolving confusion through the use ofstatistical information;

FIG. 10 is a simplified block diagram of several sample aspects ofcomponents that may be employed in a communication node;

FIG. 11 is a simplified diagram of a wireless communication system;

FIG. 12 is a simplified diagram of a wireless communication systemincluding femto nodes;

FIG. 13 is a simplified diagram illustrating coverage areas for wirelesscommunication;

FIG. 14 is a simplified block diagram of several sample aspects ofcommunication components; and

FIGS. 15-19 are simplified block diagrams of several sample aspects ofapparatuses configured to provide ambiguity resolution as taught herein.

In accordance with common practice the various features illustrated inthe drawings may not be drawn to scale. Accordingly, the dimensions ofthe various features may be arbitrarily expanded or reduced for clarity.In addition, some of the drawings may be simplified for clarity. Thus,the drawings may not depict all of the components of a given apparatus(e.g., device) or method. Finally, like reference numerals may be usedto denote like features throughout the specification and figures.

DETAILED DESCRIPTION

Various aspects of the disclosure are described below. It should beapparent that the teachings herein may be embodied in a wide variety offorms and that any specific structure, function, or both being disclosedherein is merely representative. Based on the teachings herein oneskilled in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. Furthermore,an aspect may comprise at least one element of a claim.

FIG. 1 illustrates several nodes of a sample communication system 100(e.g., a portion of a communication network). For illustration purposes,various aspects of the disclosure will be described in the context ofone or more access terminals, access points, and network nodes thatcommunicate with one another. It should be appreciated, however, thatthe teachings herein may be applicable to other types of apparatuses orother similar apparatuses that are referenced using other terminology.For example, in various implementations access points may be referred toor implemented as base stations or eNodeBs, access terminals may bereferred to or implemented as user equipment or mobile stations, and soon.

Access points in the system 100 provide one or more services (e.g.,network connectivity) for one or more wireless terminals that may beinstalled within or that may roam throughout a coverage area of thesystem 100. For example, at various points in time the access terminal102 may connect to an access point 104, any one of a set of accesspoints 1-N (represented by access points 106 and 108 and the associatedellipsis), or an access point 110.

Each of the access points 104-110 may communicate with one or morenetwork nodes (represented, for convenience, by network node 112) tofacilitate wide area network connectivity. Such network nodes may takevarious forms such as, for example, one or more radio and/or corenetwork entities. Thus, in various implementations the network node 110may represent functionality such as network management (e.g., via anoperation, administration, management, and provisioning entity), callcontrol, mobility management, gateway functions, interworking functions,or some other suitable network functionality.

Each access point in the system 100 may be assigned a first type ofidentifier that may be used to readily identify the access point. Here,the number of bits in the identifier may be relatively small so that asignal including this identifier may be easily detected by an accessterminal (e.g., even when the access terminal has an active call). Invarious implementations such an identifier may comprise, for example, aphysical cell identifier (“PCI”), a pilot pseudonoise (“PN”) offset, oran acquisition pilot. Typically, a fixed quantity of node identifiers(e.g., 500 or less) is defined for a given system. In such a case,identifier confusion may often arise when a large number of accesspoints (e.g., femto access points) are deployed in the same vicinitysince several of these access points may be assigned the sameidentifier.

An overview of how identifier confusion may be resolved in accordancewith the teachings herein will be described with reference to FIG. 1 andthe flowchart of FIG. 2. FIG. 1 illustrates a simple example where theaccess point 106 and the access point 110 are both assigned “identifier1.” As the access terminal 102 roams through the system 100, the accessterminal 102 may be handed over from a source access point (i.e., theserving access point to which the access terminal is currentlyconnected, e.g., access point 104) to a target access point (e.g.,access point 110).

For example, as represented by block 202 of FIG. 2, at some point intime the access terminal 102 receives a signal from a potential targetaccess point. This signal may comprise (e.g., include or be encoded orscrambled with) an identifier of the potential target access point suchas a pilot PN offset or a PCI. Upon receipt of this signal, the accessterminal 102 may send a message (e.g., a measurement report) includingthe identifier and an indication of the associated received signalstrength (e.g., RSSI) to its current serving access point.

As represented by block 204, a decision may be made to handover theaccess terminal 102 to the target access point. This decision may bebased, for example, on whether the access terminal 102 is receivingparticularly strong pilot signals (e.g., exceeding a threshold) fromthat target access point.

In the absence of confusion, the first identifier (e.g., identifier 1)acquired by the access terminal 102 may be unambiguously mapped to asecond identifier assigned to the target access point that is used toestablish communication with the target access point. In some aspects,the second identifier may be more unique (e.g., comprise more bits) thanthe first identifier. For example, the second identifier may be uniquewithin a larger geographic area, may be unique within an entire network(e.g., a wireless operator network) or subnet, or may be more unique insome other manner. In various implementations such an identifier maycomprise, for example, a global cell identifier (CGI), an access nodeidentifier (ANID), a cell global identification (ICGI), a sectoridentifier, or an IP address.

As represented by block 206, however, in some cases more than one accesspoint within a given area may be assigned the same first identifier. Forexample, femto access points 106 and 110 within the coverage area of asource macro access point 104 may be assigned identifier 1. Whenconfusion does exist, the source access point may not be able todetermine which access point is the desired target access point. Forexample, the access point 104 may not be able to determine whether tocommunicate with the access point 106 or the access point 110 to reserveresources for the access terminal

As represented by block 208, confusion such as this may be resolved byidentifying a target access point through the use of one or more of thetechniques described herein. For example, as described in more detailbelow in conjunction with FIGS. 3A-6, a target may be identified byrequesting potential targets to monitor for signals from the accessterminal to be handed-over and processing the results of this monitoringto determine which of these potential targets is most likely to be theintended target. In some aspects, this determination may utilize atiered target resolution scheme. In addition, as described in moredetail below in conjunction with FIGS. 7-10, one or more candidatetargets may be identified based on historical use records that aremaintained for the access terminal For example, a mapping may bemaintained that identifies a specific access point (e.g., via a CGI)that the access terminal is typically handed-off to when the accessterminal reports a given identifier (e.g. PCI).

As represented by block 210, the target access point identified at block208 is prepared for handover of the access terminal 102. Here, theserving access point (i.e., the source access point for the handover)may communicate with the target access point to reserve resources forthe access terminal. For example, context information maintained by theserving access point may be transferred to the target access pointand/or context information maintained by the target access point may besent to the access terminal 102.

As represented by block 212, the handover may then be completed assumingthe correct target access point was prepared for the handover. Here, theaccess terminal and the target access point may communicate with oneanother in accordance with conventional handover procedures.

With the above overview in mind, various techniques that may be employedto resolve confusion through the use of target monitoring in accordancewith the teachings herein will be described with reference to FIGS.3A-6. For illustration purposes, the operations of FIGS. 3A-6 (or anyother operations discussed or taught herein) may be described as beingperformed by specific components. It should be appreciated, however,that these operations may be performed by other types of components andmay be performed using a different number of components. It also shouldbe appreciated that one or more of the operations described herein maynot be employed in a given implementation.

As represented by block 302 of FIG. 3A, upon acquisition of a signalfrom a target access point, an access terminal sends a measurementreport (e.g., a pilot strength measurement message, PSMM) to its servingaccess point. As discussed above, this report includes an identifier ofthe target access point and the signal strength of the signal as it wasreceived at the access terminal In addition, as discussed in more detailbelow, in some cases the access terminal may include received pilotphase information in the report.

For example, the access terminal may identify the macro access pointsthat are known to be in the vicinity of the access terminal Here, theaccess terminal may repeatedly monitor for signals such as pilot signalsfrom nearby access points and maintain a record of those macro accesspoints from which the access terminal is able to receive signals.

As another example, the access terminal also may determine phaseinformation associated with pilot signals the access terminal receivesfrom nearby macro access points. This phase information may relate to,for example, the phase of a pilot PN sequence as observed at the accessterminal In some cases, the access terminal may select the pilot signalfrom one access point as a reference and determine the relative phase ofany other received pilot signals with respect to the reference. In someaspects phase information such as this may be used to estimate thelocation of the access terminal since, in a synchronous system, thephase delay of a signal received at the access terminal may beindicative of the distance of the access terminal from the access pointthat transmitted the signal.

As represented by block 304, a determination then be may be made thatthe access terminal should be handed-over to the target point based onthe measurement report as discussed above. This decision may be made,for example, by the serving access point and/or by a network node suchas a base station controller.

As represented by block 306, a determination is also made as to whetherthe identifier acquired by the access terminal unambiguously identifiesthe target access point. If there is no identifier confusion (e.g., noother access point within the coverage area of the serving access pointis assigned the identifier), the target access point is prepared forhandover of the access terminal (block 308).

If it is determined that there is identifier confusion at block 306,however, the operational flow instead proceeds to block 310. Here, atleast one candidate target access point may be identified based onvarious criteria (e.g., a historical use record). These criteria aredescribed in more detail below in conjunction with FIG. 4A.

Briefly, in some cases information may be maintained that identifies aparticular type of access point to which the access terminal is likelyto go to when the access terminal is in the coverage area of the servingaccess point. Such an access point may include, for example, a homefemto access point and/or an office femto access point. In this case,this access point (or these access points) may be identified as thecandidate access point(s) at block 310.

In addition, in some cases information may be maintained that identifiesthe access point(s) that the access terminal has previously used (e.g.,accessed). Here, if the access terminal has used a given access point inthe past, it may is assumed that the access terminal may use that accesspoint again. Hence, this access point (or these access points) may beidentified as the candidate access point(s) at block 310.

In some cases there may not be any information that limits the accesspoints to be considered at block 310. In these cases, all of the accesspoints that are known to be assigned the confusion identifier and thatare within the coverage area of the serving access point may beidentified as the candidate access point(s) at block 310.

As represented by block 312, a message is sent to each access pointidentified at block 310. Each message comprises a request to a candidateaccess point to monitor for a signal from the access terminal (i.e., theaccess terminal that sent the report at block 302). To this end, themessage may include an identifier associated with the access terminal toenable the candidate access point to acquire a signal from the accessterminal. For example, the identifier may comprise a long code mask(e.g., used by the access terminal to encode or scramble its messages)or some other suitable identifier.

The receipt of such a message at a candidate access point is representedby block 314. The candidate access point then monitors for the signal(e.g., attempts to acquire the reverse link) as represented by block316.

As represented by block 318 of FIG. 3B, a determination is then made asto whether the candidate access point is able to receive such a signal.If the candidate access point did not receive this signal, the candidateaccess point may send a negative acknowledgement (NACK) response or notsend any response at block 320. In some implementations the candidateaccess point may send a negative acknowledgement or not send a responseif there is an invalid (e.g., poor) measurement result associated withthe received signal (e.g., the candidate access point measures a lowsignal level).

Here, it should be appreciated that it is unlikely that an access pointthat is relatively far away from the access terminal would be able toreceive a signal (e.g., a sufficiently valid signal) from the accessterminal Such an access point may be eliminated for consideration asbeing the target access point given that it may be unlikely that theaccess terminal would have received a signal of sufficient magnitudefrom this far-off access point. In other words, it may be highlyunlikely that the signal acquired by the access terminal at block 302originated from this far-off access point.

Conversely, it may be expected that an access point that is relativelyclose to the access terminal would be able to receive a signal (e.g., asufficiently valid signal) from the access terminal. In this case, itmay be highly likely that the access terminal would have received asignal of sufficient magnitude from this nearby access point. Hence, anearby access point such as this is likely to be the intended handovertarget.

As represented by block 322, in the event the candidate access pointreceived a signal from the access terminal (e.g., a signal with asufficient signal level), the candidate access point sends a responsemessage that indicates the signal was received. The response may includean indication of the received signal strength of this signal as measuredat the candidate access point.

The response also may include neighbor list information, received pilotphase information, and transmit power information. For example, acandidate access point may be configured to obtain information thatidentifies the macro access points that are in the vicinity of thecandidate access point. In some cases this information may be obtainedfrom the network (e.g., when the candidate access point is deployed orperiodically). Alternatively, or in addition, in cases where thecandidate access point has forward link monitoring capabilities, theaccess point may repeatedly monitor for signals such as pilot signalsfrom nearby access points and maintain a record of those macro accesspoints from which the access point is able to receive signals. In atypical case, access points (e.g., femto access points) in a networkwill report the above information (e.g., to a femto convergence server)at some point in time prior to sending the response. For example, thisinformation may be reported when the candidate access point is deployedand/or periodically.

The candidate access point also may determine phase information (e.g.,phase delay) associated with pilot signals the access point receivesfrom nearby macro access points. In a similar manner as discussed aboveat block 302, this phase information may be used to estimate thelocation of the candidate access point.

The receipt of the response message(s) from the candidate accesspoint(s) is represented by block 324 of FIG. 3. In some implementations,a negative response (e.g., a NACK response) or a response that isassociated with an invalid measurement result (e.g., a response withpoor measurement results from a candidate access point that measured alow signal level) may be ignored (e.g., discarded). In this way,scalability may be improved since fewer responses may need to beconsidered (e.g., by a network node that receives the responses) toidentify the target.

As represented by block 326, the target access point is identified basedon the response(s). For example, if only one valid affirmative responseis received, it may be assumed that the candidate access point that sentthe response is the actual target access point.

Conversely, if more than one affirmative response is received, a singletarget access point may be selected from the candidate access points.Here, multiple affirmative responses may be received, for example, incases where the access terminal has a relatively high transmit powerand/or in cases where the access terminal is relatively close tomultiple access points that are assigned the same identifier.

In some cases the target access point is selected based on the receivedsignal strength indications provided in the responses. For example, thecandidate access point that has the highest received signal strength maybe selected as the target access point.

It some cases another criterion may be used to select the target accesspoint. For example, if comparable received signal strength indicationsare received from different candidate access points, this informationmay not resolve the confusion.

In addition, in some cases the highest received signal strength may notbe a conclusive indication of the actual target access point. Forexample, in a case where different femto access points have differenttransmit powers, an access terminal that is closer to a first femtoaccess point (that transmits at low power) may have received a strongerpilot signal from a second femto access point (that transits at a highpower) that is farther away from the access terminal Hence, the secondfemto access point may be the true target access point under thesecircumstances. However, the first access may report a higher receivedsignal strength since it is closer to the access terminal

In some cases the target access point is selected based, in part, ontransmit power information provided in the responses. For example, bydetermining that one candidate access point transmits at a lower powerlevel than another, it may be determined that some criterion other thanreceived signal strength should be used to select the target accesspoint.

In some cases the target access point is selected based on the phaseinformation provided in the responses. Here, the phase informationprovided by the access terminal at block 302 may be compared with thephase information provided in each response (e.g., accounting for timingreference differences, as necessary). The candidate access point thatprovides phase information that most closely matches that of the accessterminal (thereby indicating that this access point is closest to accessterminal) may be selected as the target access point. Alternatively,this comparison may simply be used to eliminate the access points thathave phase information that is considerably different than the phaseinformation of the access terminal In some aspects, such a phaseinformation-based selection scheme may be particularly effective if thecoverage of the access point is relatively small. If the coverage of theaccess point is large, however, such a scheme may not be as reliable.

In some cases the target access point is selected based on the neighborlist information provided in the responses. Here, the pilot measurementinformation provided by the access terminal at block 302 (e.g., pilotreports regularly provided by the access terminal over a period of timethat identify one or more access points seen by that access terminal)may be compared with the neighbor list information provided in eachresponse. The candidate access point that provides neighbor listinformation that most closely matches the pilot measurement informationof the access terminal (thereby indicating that this access point isclosest to access terminal) may be selected as the target access point.Alternatively, this comparison may simply be used to eliminate theaccess points that have a neighbor list that is considerably differentthan the pilot measurement information of the access terminal

As represented by block 328, once the target access point is identified,appropriate operations are commenced to complete the handover of theaccess terminal to the target access point.

As mentioned above, confusion resolution as taught herein may be basedon historical use records and/or involve a tier-based resolution scheme.Several examples of these aspects of the disclosure will be describedwith reference to FIG. 4A.

As represented by block 402, historical use information may bemaintained in a system by tracking certain events associated with accessterminals and/or access points in the system. This information may bestored in a memory device in various ways including, for example, as asimple data record or as entries in a formal database.

In some aspects the tracked events may be indicative of which accesspoints have been or will be used by which access terminals. In somecases the system may be informed whenever an access terminal is firstassociated with a home femto access point. In some cases the system maytrack registration operations by an access terminal to determine wherethe access terminal has previously registered. In some cases the systemmay update a database entry each time an access terminal originates,terminates or hands-over a call with a given femto access point. In somecases the system may track handover operations to determine where agiven access terminal is usually handed-over upon reporting a givenidentifier. For example, each time a handover is requested, the systemmay update handover counts and success rates. This may be useful in someaspects for algorithm evaluation, tier classification, and systemconfiguration quality (e.g., identifier assignment algorithmassessment). In some cases, information acquisition as taught herein maybe implemented in conjunction with billing record generation. In somecases, when a femto access point is activated, the system may learn theidentifier (e.g., pilot PN offset) and macro neighbor list of the femtoaccess point. It should be appreciated that other techniques may beemployed to determine whether, when, or how frequently a given accessterminal has accessed (or attempted to access) one or more accesspoints.

An example of a database structure follows with reference to FIG. 4B. Ata first (highest) level of the database structure, the database includesone or more macro access point entries. In this way, information aboutaccess terminal usage within the coverage area of a given macro accesspoint in the system may be tracked. Each of the macro access pointentries may be identified by a corresponding unique macro access pointidentifier (e.g., base station IDs: BS-ID 1, BS-ID 2, etc.). When afemto access point has multiple macro access point neighbors, databaseinformation for that femto access point within the coverage area of agiven macro access point may be accessed using the corresponding macroaccess point identifier.

Each macro access point entry includes second level entries fordifferent femto access point identifiers of a first type (e.g., pilot PNoffsets, PCIs). For example, the first time such an identifier is usedwithin the coverage area of a given macro access point, a second levelentry (e.g., PILOT PN OFFSET 1) may be created for that identifier underthe first level entry for that macro access point (e.g., BS-ID 1). Anysubsequent use of the identifier may then result in the identifier entrybeing updated.

Each femto access point identifier entry, in turn, includes third levelentries for different femto access point identifiers of a second type(e.g., unique identifiers such as CGIs). For example, when a femtoaccess point that is assigned a given pilot PN offset (e.g., PILOT PNOFFSET 1) is used within the coverage area of a given macro accesspoint, a third level entry (e.g., FEMTO ID 1) may be created for theunique identifier assigned to that same access point. In this way,information may be maintained regarding the different access points thatuse the same pilot PN offset within the coverage area of a given macroaccess point.

Each third level femto access point identifier entry, in turn, includesfourth level entries for different access terminals that use thatspecific access point. For example, when an access terminal accesses agiven femto access point within the coverage area of a given macroaccess point, a fourth level entry (e.g., AT ID 1) may be created forthat access terminal In this way, information may be maintainedregarding the different access terminals that use particular accesspoints within the coverage area of a given macro access point. Each ofthe access terminal entries may be identified by a corresponding uniqueaccess terminal identifier.

Each access terminal entry, in turn, includes fifth level entriesrelating to access point use by that access terminal For example, oneentry (e.g., entry 1) may identify the home femto access point(s) forthat access terminal. One entry (e.g., entry 2) may indicate the mostrecent time (e.g., time of day and/or date) that the access terminalaccessed the corresponding access point (corresponding to level three ofthis branch of the structure). One entry (e.g., entry 3) may indicatehow many times the access terminal accessed the corresponding accesspoint. One entry (e.g., entry 4) may indicate how many times (e.g., alifetime count) the access terminal was a first tier handover candidate.One entry (e.g., entry 5) may indicate how many times (e.g., a lifetimecount) the access terminal was correctly identified as a first tierhandover candidate. Similar handover candidate entries may be providedfor a second tier, a third tier, etc.

Various provisions may be employed to maintain the database. Forexample, if a femto access point location changes, the records for thatfemto access point may be started anew. Also, if the size of thedatabase becomes excessive, staler entries may be removed in favor ofnewer entries.

For purposes of illustration, an example of how database information maybe used in a scheme that uses a tiered set of criteria for identifyingcandidate target access points follows. In this example, different setsof candidate target access points are defined for each tier, whereby theaccess points in the tiers may be requested to monitor for a signal fromthe access terminal on a tier-by-tier basis. Here, in the event theoperations for a given tier do not resolve identifier confusion, broadertargeting may be employed at the next tier. The operations of a giventier may fail to resolve the confusion because, for example, there wasno handover candidate at that tier that was able to receive a signalfrom the access terminal Similarly, under various conditions a giventier may be skipped (e.g., if there is no record for that tier that ishelpful in reducing ambiguity).

Four tiers are defined in the example that will now be described withreference to FIG. 4A. In the first tier, the set of candidate accesspoints consists of the home femto access point of the access terminal Inthe second tier, the set of candidate access points consists of theaccess points that the access terminal has used in the past. In thethird tier, the set of candidate access points consists of femto accesspoints that have a neighbor list that matches the pilot measurementreported by the access terminal Alternatively, the third tier consistsof the access points that have similar pilot phase information with thepilot measurement reported by the access terminal In the fourth tier,the set of candidate access points consists of all other femto accesspoints that have been assigned the confusing identifier and that havethe serving macro access point for the access terminal as a neighbor. Insome aspects, each of the tiers may be defined to only identify accesspoints that the access terminal is allowed to access (e.g.,corresponding to an associated closed subscriber group). For example, ifan access point is restricted and the access terminal does not havepermission to access that access point, that access point will not beincluded in a tier entry.

As represented by block 404 of FIG. 4A, at some point in time it may bedetermined that an identifier reported by an access terminal is subjectto confusion. The first confusion resolution tier (highest tier) maythen be selected at block 406.

As represented by block 406, one or more candidate target access pointsare selected based on the tier 1 criterion or criteria. In this example,tier 1 involves selecting the home femto access point for the accessterminal.

As represented by block 408, an attempt is made to resolve the confusionbased on the tier 1 criterion or criteria. In this case, a request tomonitor for a signal from the access terminal is sent to the home femtoaccess point identified at block 406. A target determination may then bemade based on whether a response is received and, if so, the result ofthat response. For example, if the home femto access point received thesignal from the access terminal, it may be determined that the homefemto access point is the intended target (which will typically be thecase) and, hence, the confusion is deemed resolved. Conversely, if thehome femto access point did not receive the signal, the confusion hasnot been resolved.

As represented by block 412, if the confusion has been resolved, theoperational flow proceeds to block 414. Here, the target identified atblock 410 is prepared for handover and the handover operations mayproceed as discussed herein.

In the event the confusion was not resolved based on the first tieroperations, as represented by blocks 412 and 406, the next (second) tiermay be selected. Continuing with the above example, a monitor requestmay be sent to each femto access point of the set of femto access pointsthat the access terminal previously used. If only one of these accesspoints sends a response indicating that the signal was received from theaccess terminal, it may be deemed that the confusion is resolved.However, if more than one access point sends a response indicating thatthe signal was received, further processing may be performed to narrowthe number of candidate targets. For example, the received signalstrength indications sent with the responses may be compared in anattempt to determine which access point is closest to the accessterminal (and, hence, is most likely to be the target).

In the event the confusion was not resolved based on the second tieroperations, the third tier may be selected as the process flow againproceeds from block 412 to block 406. Here, a monitor request may besent to each femto access point of the set of femto access point thathave a neighbor list that matches the pilot measurement information ofthe access terminal As above, the confusion may be deemed resolved ifonly one affirmative response is received while further processing maybe performed if multiple affirmative responses are received.

In the event the confusion was not resolved based on the third tieroperations, the fourth tier may be selected as the process flow againproceeds from block 412 to block 406. Here, a monitor request may besent to each femto access point of the set of femto access points thathave the same identifier and have the macro access point as a neighbor.As above, the confusion may be deemed resolved if only one affirmativeresponse is received while further processing may be performed ifmultiple affirmative responses are received.

As represented by block 414, the database may be updated at some pointduring the operations of FIG. 4A based on the result of theseoperations. For example, if a given access point was identified as asecond tier candidate access point, a corresponding database entry maybe updated. Also, if the access terminal was successfully handed-over toa particular access point, another database entry may be updated.

The operations of multiple tiers may be combined in some cases. Forexample, phase information and/or neighbor lists provided by candidateaccess points may be compared to the corresponding information providedby the access terminal to reduce ambiguity at a given tier, to prunecandidate access points, or to double-check the candidate access pointsidentified by at least one other tier. In this case, the comparison maybe used to determine which access point is closest to the accessterminal (e.g., through the use of triangulation techniques).

The operations described above may be performed by various entities in anetwork. For example, in some implementations confusion resolutionoperations (e.g., one or more of blocks 208, 310, 312, 324, 326, and406-412) may be performed by a network node (e.g., a femto convergenceserver (FCS) or femto mobile switching center (F-MSC)) that managesmobility operations for a set of femto access points in the network. Inother implementations one or more of these operations may be performedby some other type of node (e.g., an access point controller or accesspoint).

FIG. 5 illustrates several sample components that may be incorporatedinto nodes such as an access point 502 and a network node 504 to performconfusion resolution operations as taught herein. The describedcomponents also may be incorporated into other nodes in a communicationsystem. For example, other nodes in a system may include componentssimilar to those described for the access point 502 and the network node504 to provide similar functionality. Also, a given node may contain oneor more of the described components. For example, an access point maycontain multiple transceiver components that enable the access point tooperate on multiple frequencies, operate on different types of links(e.g., uplink and downlink), and communicate via different technologies.

As shown in FIG. 5, the access point 502 includes a transceiver 506 tofacilitate wireless communication with other nodes. The transceiver 506includes a transmitter 508 for sending signals (e.g., pilot signals andother signals) and a receiver 510 for receiving signals (e.g.,measurement reports and other signals).

The access point 502 and the network node 504 include network interfaces512 and 514, respectively, for communicating with other network nodes(e.g., sending and receiving monitor requests and responses). Forexample, each network interface may be configured to communicate withone or more network nodes via a wired or wireless backhaul.

The access point 502 and the network node 504 also include othercomponents that may be used in conjunction with confusion resolutionoperations as taught herein. For example, the access point 502 and thenetwork node 504 may include communication controllers 516 and 518,respectively, for managing communication with other nodes (e.g., sendingand receiving messages, reports, responses, and other information) andfor providing other related functionality as taught herein. In addition,the access point 502 and the network node 504 may include handovercontrollers 520 and 522, respectively for performing handover-relatedoperations (e.g., determining whether and how to perform a handover,determining whether there is confusion and resolving the confusion,identifying access points for handover, sending and receiving messages)and for providing other related functionality as taught herein.

Referring to FIG. 6, for purposes of explanation, an active statehandover (e.g., hand-in) procedure will be described in detail in thecontext of a 3GPP2 system. It should be appreciated that the teachingsherein may be applicable to other types of system (e.g., LTE, UMTS,etc.).

Initially, a handover stimulus may involve a macro base stationcontroller (source BSC) receiving a PSMM from an access terminal (AT).This report includes the PN offset the AT acquired from a target femto.Upon determining that the PN offset is associated with a femto accesspoint, the macro network (e.g., by operation of the source BSC and MSC)initiate handover by requesting the assistance of the femto system(e.g., the target FCS) in resolving the PN offset to a unique target ID(e.g., cell global identification). This request (e.g., femto monitorrequired) may include the PN offset reported by the AT, a mobileidentifier of the AT, a long code mask used by the AT on the reverselink, an identifier of the serving access point (not shown in FIG. 6),and, optionally, other information (e.g., a neighbor list, etc., asdescribed herein).

In response to the request, the target FCS conducts a database lookupfor candidate femto access points that are assigned the PN offset. Thislookup may involve the use of various parameters (e.g., home femtoidentifiers, use information, phase information, neighbor lists) astaught herein. In addition, this lookup may involve a tiered scheme astaught herein. Thus, the target FCS may first determine whether the homefemto access point has the confusing identifier at tier 1, thendetermine if any femto access points previously used by the AT have theconfusing identifier at tier 2, and so on. In the event the AT isrepeatedly handed-over between a given femto access point and the sourceBSC, this scenario may be detected, whereby the set for a tier (e.g.,the second tier) may be reduced to a signal candidate femto accesspoint.

In the example of FIG. 6, the target FCS sends a request to three femtoaccess points to monitor (e.g., acquire) the reverse link. Each of theserequests includes the long code mask for the reverse link. The femtoaccess points then monitor the reverse link to detect the AT. The femtoaccess points that detect the AT (two access points in this example)make signal measurements on the reverse link.

Next, each of the femto access points sends a response (e.g., femtomonitor response) to the target FCS. Each of the responses from thefemto access points that detected the AT includes an identifier of thefemto access point (e.g., cell global identification), an indicationthat the monitoring was successful, and the reverse link signalmeasurement. The response from the femto access point that did notdetect the AT may include an identifier of the femto access point and anindication that the monitoring was unsuccessful.

The target FCS identifies the target access point based on the receivedreverse link signal measurement values and/or in some other criterion orcriteria. The target FCS may then send a clear command to the other twoaccess points so that those access points may de-allocate theirresources.

The target FCS also sends an acknowledgement (e.g., femto monitor ack)to the macro network (e.g., the source MSC). This message may include,for example, the status of the monitoring (e.g., success or failure),the identifier of the identified target femto, a mobile identifier ofthe AT, and, optionally, other information. The macro network may thenproceed with handover operations so that the AT is directed to thetarget femto access point.

In view of the above it may be seen that various advantages may beprovided by a system constructed in accordance with the teachingsherein. In some aspects, such a system may provide scalability withoutadding excessive complexity to the system. For example, the describedschemes may allow for mass deployment of femto access points since theresulting identifier ambiguity may be adequately resolved. Also, thedescribed handover procedures enable identifier ambiguity to be resolvedwith little impact on the system architecture and on the macro system.For example, handovers may be achieved without excessive networkresource usage, and streamlined signaling procedures may be employed.Also, no base station or radio interface changes may be required toimplement the described confusion resolution scheme on a legacy system.For example, for a legacy 3GPP2 system, there may be little or no effecton the A/Abis interface in the macro system, there may only be two newmessages (e.g., femto monitor required and femto monitor ack) addedbetween the macro system and the femto system, and there may be no majoreffect on BSC procedures.

As mentioned above, confusion associated with handover of a given accessterminal may be resolved by maintaining a record of the access pointsthat the access terminal previously accessed and using that informationto identify one or more candidate access points for the handover. Forexample, a situation may occur where an access terminal X is to behanded-over from a macro access point Y to a femto access point Z, butit is determined that PCI z (broadcast by femto Z) is confusing. Thereare many ways of resolving the confusion of PCI z (e.g., through askingthe access terminal to report the global cell ID of femto access pointZ). Once the confusion is resolved, macro access point Y will know that“access terminal X went from macro access point Y to femto access pointZ”. In practice, it is quite likely that access terminal X will repeatthis path in the future since a given access terminal is typicallyassociated with only a small number of femto access points. For example,the majority of the times that access terminal X ends up on a femtoaccess point is when access terminal X is going home or to a favoritecoffee shop. To anticipate such a future event, macro access point Y maycache information indicating that “For access terminal X, PCI ztypically resolves to femto access point Z”. In some cases macro accesspoint Y may cache information about several optional femto access pointsZ1, Z2, . . . Zk if access terminal X tends to visit multiple targetsthat are assigned the same PCI.

Macro access point Y may then use the cached information in the eventaccess terminal X reports PCI z at some point in the future. That is, ifmacro access point Y receives PCI z from access terminal X in ameasurement report, macro access point Y prepares femto access point Z(or femto access points Z1, Z2, . . . Zk) since the past history foraccess terminal X indicates that femto access point Z (or one of femtoaccess points Z1, Z2, . . . Zk) is probably the intended target. Such ascheme may be useful when the preparation of a large number of targetsis not feasible due to resource or other constraints (i.e., where it isdesirable to only prepare a limited number of targets).

A history-based scheme also may be useful in a case where a macro accesspoint does not know the use history of a specific access terminal X. Forexample, a macro access point Y may use statistics based on informationthat was cached for other access terminals regarding a likelihood of howoften the other access terminals tend to visit target femto accesspoints Z1, Z2, . . . Zk when being handed-over from macro access pointY. Based on this statistical information, macro access point Y mayprepare one or more of Z1, Z2, . . . Zk when attempting to handoveraccess terminal X. The number of such femto access points that macroaccess point Y prepares may be limited by resource constraints, byconfiguration, or any other method.

Sample operations that may be performed to provide accessterminal-specific use-based confusion resolution such as this will nowbe described in some detail in conjunction with the flowcharts of FIGS.7-9. Briefly, FIG. 7 describes operations that may be performed at anode such as a source access point to handover an access terminal FIG. 8describes operations that may be performed in conjunction withmaintaining (e.g., creating and updating) a use information database.FIG. 9 describes operations that may be performed to resolve confusionbased on statistical information.

As represented by block 702 of FIG. 7, at some point in time a mappingis determined, wherein the mapping maps a first access point identifier(e.g., PCI) used by an access terminal to identify a target access pointwith another access point identifier (e.g., CGI) that more uniquelyidentifies the intended target access point. As mentioned above, thismapping may be based on historical use information acquired for theaccess terminal For example, the mapping may indicate that when theaccess terminal X reports PCI z to macro access point Y, the accessterminal is usually (or always) handed-over to femto access point Z.Similar mappings may be determined for this access terminal for thissame first identifier (i.e., mappings to other second identifiersassociated with other femto access points) in situations wherein theaccess terminal has accessed more than one access point with the sameidentifier. Similar mappings also may be determined for this accessterminal for other first identifiers (i.e., mappings to another set ofother second identifiers). In addition, similar mappings may bedetermined for other access terminals that have reported a firstidentifier to macro access point Y.

As represented by block 704, information indicative of each mappingdetermined at block 702 is stored in a memory device. In someimplementations the operations of blocks 702 and 704 are performed ateach macro access point in a network. Hence, mapping information may bemaintained at each of these macro access points.

The historical use information used to create the above mappings may beobtained in various ways. Several examples of how such information maybe obtained during the course of standard operations will be describedwith reference to FIGS. 8A-8C.

As represented by block 802 of FIG. 8A, as an access terminal travelsthroughout a network, the access terminal may receive signals (e.g.,pilot signals) from nearby access points. The access terminal may thenreport receipt of these signals (e.g., via a measurement report) to itsserving access point.

In some cases, the access terminal may acquire more than one type ofidentifier from a nearby access point. For example, the access terminalmay acquire both the PCI and the CGI from the nearby access point. Insuch a case, the access terminal may elect to report both of theseidentifiers to its serving access point.

Accordingly, as represented by block 804, the serving access point mayupdate its database based on the identifiers provided in the report.Thus, in some cases an access terminal-specific mapping between twoidentifiers may be determined based solely on identifier informationprovided by the access terminal via a measurement report or some othersimilar report.

Referring now to FIG. 8B, in some cases the serving access pointrequests the assistance of the access terminal to resolve confusion. Forexample, as represented by block 806, an access terminal may provide ameasurement report (or some other report) that only includes a firstidentifier (e.g., PCI) of a target access point. As represented by block808, the serving access point may determine that there is confusionassociated with the use of this first identifier and send a request tothe access terminal to monitor for a second identifier (e.g., a moreunique identifier such as a CGI) from the target access point to resolvethe confusion. Upon acquiring this information (if possible), the accessterminal sends the requested confusion resolution information to theserving access point at block 810 (e.g., via another measurement reportincluding the CGI). The serving access point may then update itsdatabase based on the identifiers provided in the reports (block 812).

FIG. 8C illustrates another case where the measurement report (or someother report) provided by an access terminal at block 814 only includesa first identifier (e.g. PCI) of a target access point. In this case,the serving access point may update its database to maintain a recordindicating that this particular access terminal has reported a givenidentifier (block 816).

In addition, the serving access point for the access terminal maydetermine that there is confusion associated with this identifier. Here,the access terminal may perform appropriate procedures to resolve thisconfusion in an attempt to handover the access terminal to the desiredtarget (e.g., prepare multiple targets for handover as discussedherein).

As represented by block 818, the serving access point may obtaininformation about a second identifier associated with the recorded firstidentifier in the event the access terminal ends up at the target accesspoint after reporting the identifier to the serving access point. Forexample, if the access terminal is successfully handed-over to a targetaccess point, the serving access point may receive a handover-relatedmessage (e.g., a handover complete message) from the target access pointthat provides the second identifier of the target access points. Thus,this message may be used to determine that when the access terminalreports a given first identifier, the access terminal ends up beinghanded over to an access point having the second identifier.

Alternatively, in some cases the access terminal experiences a radiolink failure (RLF) after reporting the first identifier and ends upconnected to the target access point after recovering from the RLF. Inthese cases, the serving access point may receive a message (e.g., anRLF report or an explicit context fetch) from the target access pointthat indicates that the access terminal ended up there. In either case,the serving access point may update the database based on the secondidentifier included in the received message.

Referring again to FIG. 7, at some point in time after the mappinginformation has been maintained at blocks 702 and 704, an accessterminal reports an identifier as represented by block 706. If there isno confusion for this identifier at block 708, the corresponding targetaccess point is prepared for handover of the access terminal (block710).

In the event confusion was identified at block 708, the stored mappinginformation is used to resolve the confusion at block 712. For example,as discussed above, the access point at which the access terminaltypically ends up after reporting the identifier may be identified as acandidate access point. Alternatively, in the event the access terminalhas, on different occasions, ended up at different ones of a set ofaccess points having the same first identifier, each of the accesspoints in the set may be identified as a candidate access point. In thisway, the access terminal may be successfully handed-off to one of thesecandidate access points. The other candidate access points may thendeallocate resources once they determine (e.g., after a timeout period)that the access terminal is not being handed-over to them.

As represented by block 714, appropriate messages may then be sent toeach of the candidate access points identified at block 712 to preparethe candidate access point(s) for handover of the access terminal Insome implementations, neighbor access points of the candidate accesspoints also may be prepared for handover of the access terminal

FIG. 9 describes sample operations that may be performed, for example,in a situation where there is no prior use information available for anaccess terminal to be handed-over. In this case, confusion resolution isresolved through the use of a probability based on the history of accessterminals that have used the same identifier.

As represented by block 902, at various point in time a node (e.g., amacro access point) receives information that indicates that differentaccess terminals in the node's coverage area may use the same identifier(e.g., a PCI) to identify different target access points. Thisinformation may be acquired, for example, in a similar manner asdescribed in FIG. 8.

As represented by block 904, statistical information is provided (e.g.,generated) based on the information acquired at block 902 and stored ina memory device. In some implementations the statistical information(e.g., a statistical distribution) is indicative of the probability thata given one of the access points that have the confusing identifier isthe intended target during a given handover directed to that identifier.For example, a first access point may have ended up as the target 40% ofthe time that the identifier was reported to a macro access point, asecond access point may have ended up as the target 30% of the time thatthe same identifier was reported to the macro access point, and so on.Here, it is noted that different access terminals may have reported thedifferent target access points.

As represented by block 906, at some point in time after the statisticalinformation has been maintained at blocks 902 and 904, an accessterminal reports the same identifier. As represented by blocks 908 and910, if a mapping is maintained for this access terminal, the mappingmay be used to resolve confusion for this access terminal (e.g., asdiscussed above at FIG. 7).

As represented by block 912, if a mapping is not maintained for thisaccess terminal, the stored statistical information may instead be usedto resolve confusion for this access terminal For example, if thestatistical information indicates that one femto access point ends upbeing the target 90% of the time that the confusing identifier wasreported to a macro access point, a decision may be made to designatethis femto access point as the candidate access point for handover ofthe access terminal Conversely, if the statistical information indicatesthat two femto access points end up being the target 85% of the timethat the confusing identifier was reported to this macro access point, adecision may be made to designate each of these femto access points as acandidate access point for handover of the access terminal.

As represented by block 914, appropriate messages may then be sent toeach of the candidate access points identified at block 912 to preparethe candidate access point(s) for handover of the access terminal

FIG. 10 illustrates several sample components that may be incorporatedinto one or more nodes (represented, for convenience, by node 1000) suchas an access point, a network node, or some other type of node toperform confusion resolution operations as taught herein. For example,the node 1000 may include a communication controller 1002 for managingcommunication (e.g., sending and receiving messages, reports,identifiers, and other information) with other nodes, and for providingother related functionality as taught herein. In addition, the node 1000may include a handover controller 1004 for performing handover-relatedoperations (e.g., determining whether and how to perform a handover,determining whether there is confusion and resolving the confusion,identifying access points for handover, sending and receiving messages),and for providing other related functionality as taught herein. The node1000 also may include a mapping controller 1006 and associated memorydevice 1008 for determining a mapping for an access terminal and storinginformation indicative of the mapping, and for providing other relatedfunctionality as taught herein. Also, in some implementations the node1000 may include a statistics controller 1010 for providing statisticalinformation (e.g., acquiring and calculating) and storing thestatistical information, and for providing other related functionalityas taught herein.

For convenience the node 1000 is shown in FIG. 10 as includingcomponents that may be used in the various examples described above inconjunction with FIGS. 7-9. In practice, one or more of the illustratedcomponents may not be used in a given example. As an example, in someimplementations the node 1000 may not comprise the statistics controller1010.

As discussed above, the teachings herein may be employed in a networkthat includes macro scale coverage (e.g., a large area cellular networksuch as a 3G network, typically referred to as a macro cell network or aWAN) and smaller scale coverage (e.g., a residence-based orbuilding-based network environment, typically referred to as a LAN). Asan access terminal (AT) moves through such a network, the accessterminal may be served in certain locations by access points thatprovide macro coverage while the access terminal may be served at otherlocations by access points that provide smaller scale coverage. In someaspects, the smaller coverage nodes may be used to provide incrementalcapacity growth, in-building coverage, and different services (e.g., fora more robust user experience).

As in the above discussion, an access point that provides coverage overa relatively large area may be referred to as a macro access point whilean access point that provides coverage over a relatively small area(e.g., a residence) may be referred to as a femto access point. Itshould be appreciated that the teachings herein may be applicable toaccess points associated with other types of coverage areas. Forexample, a pico access point may provide coverage (e.g., coverage withina commercial building) over an area that is smaller than a macro areaand larger than a femto area. In various applications, other terminologymay be used to reference a macro access point, a femto access point, orother access point-type nodes. For example, a macro access point may beconfigured or referred to as an access node, base station, access point,eNodeB, macro cell, and so on. Also, a femto access point may beconfigured or referred to as a Home NodeB, Home eNodeB, access pointbase station, femto cell, and so on. In some implementations, an accesspoint may be associated with (e.g., divided into) one or more cells orsectors. A cell or sector associated with a macro access point, a femtoaccess point, or a pico access point may be referred to as a macro cell,a femto cell, or a pico cell, respectively.

FIG. 11 illustrates an example of a wireless communication system 1100,configured to support a number of users, in which the teachings hereinmay be implemented. The system 1100 provides communication for multiplecells 1102, such as, for example, macro cells 1102A-1102G, with eachcell being serviced by a corresponding access point 1104 (e.g., accesspoints 1104A-1104G). As shown in FIG. 11, access terminals 1106 (e.g.,access terminals 1106A-1106L) may be dispersed at various locationsthroughout the system over time. Each access terminal 1106 maycommunicate with one or more access points 1104 on a forward link (FL)and/or a reverse link (RL) at a given moment, depending upon whether theaccess terminal 1106 is active and whether it is in soft handoff, forexample. The wireless communication system 1100 may provide service overa large geographic region. For example, macro cells 1102A-1102G maycover a few blocks in a neighborhood or several miles in ruralenvironment.

FIG. 12 illustrates an exemplary communication system 1200 where one ormore femto access points are deployed within a network environment.Specifically, the system 1200 includes multiple femto access points 1210(e.g., femto access points 1210A and 1210B) installed in a relativelysmall scale network environment (e.g., in one or more user residences1230). Each femto access point 1210 may be coupled to a wide areanetwork 1240 (e.g., the Internet) and a mobile operator core network1250 via a DSL router, a cable modem, a wireless link, or otherconnectivity means (not shown). As will be discussed below, each femtoaccess point 1210 may be configured to serve associated access terminals1220 (e.g., access terminal 1220A) and, optionally, other (e.g., hybridor alien) access terminals 1220 (e.g., access terminal 1220B). In otherwords, access to femto access points 1210 may be restricted whereby agiven access terminal 1220 may be served by a set of designated (e.g.,home) femto access point(s) 1210 but may not be served by anynon-designated femto access points 1210 (e.g., a neighbor's femto accesspoint 1210).

FIG. 13 illustrates an example of a coverage map 1300 where severaltracking areas 1302 (or routing areas or location areas) are defined,each of which includes several macro coverage areas 1304. Here, areas ofcoverage associated with tracking areas 1302A, 1302B, and 1302C aredelineated by the wide lines and the macro coverage areas 1304 arerepresented by the larger hexagons. The tracking areas 1302 also includefemto coverage areas 1306. In this example, each of the femto coverageareas 1306 (e.g., femto coverage areas 1306B and 1306C) is depictedwithin one or more macro coverage areas 1304 (e.g., macro coverage areas1304A and 1304B). It should be appreciated, however, that some or all ofa femto coverage area 1306 may not lie within a macro coverage area1304. In practice, a large number of femto coverage areas 1306 (e.g.,femto coverage areas 1306A and 1306D) may be defined within a giventracking area 1302 or macro coverage area 1304. Also, one or more picocoverage areas (not shown) may be defined within a given tracking area1302 or macro coverage area 1304.

Referring again to FIG. 12, the owner of a femto access point 1210 maysubscribe to mobile service, such as, for example, 3G mobile service,offered through the mobile operator core network 1250. In addition, anaccess terminal 1220 may be capable of operating both in macroenvironments and in smaller scale (e.g., residential) networkenvironments. In other words, depending on the current location of theaccess terminal 1220, the access terminal 1220 may be served by a macrocell access point 1260 associated with the mobile operator core network1250 or by any one of a set of femto access points 1210 (e.g., the femtoaccess points 1210A and 1210B that reside within a corresponding userresidence 1230). For example, when a subscriber is outside his home, heis served by a standard macro access point (e.g., access point 1260) andwhen the subscriber is at home, he is served by a femto access point(e.g., access point 1210A). Here, a femto access point 1210 may bebackward compatible with legacy access terminals 1220.

A femto access point 1210 may be deployed on a single frequency or, inthe alternative, on multiple frequencies. Depending on the particularconfiguration, the single frequency or one or more of the multiplefrequencies may overlap with one or more frequencies used by a macroaccess point (e.g., access point 1260).

In some aspects, an access terminal 1220 may be configured to connect toa preferred femto access point (e.g., the home femto access point of theaccess terminal 1220) whenever such connectivity is possible. Forexample, whenever the access terminal 1220A is within the user'sresidence 1230, it may be desired that the access terminal 1220Acommunicate only with the home femto access point 1210A or 1210B.

In some aspects, if the access terminal 1220 operates within the macrocellular network 1250 but is not residing on its most preferred network(e.g., as defined in a preferred roaming list), the access terminal 1220may continue to search for the most preferred network (e.g., thepreferred femto access point 1210) using a Better System Reselection(BSR), which may involve a periodic scanning of available systems todetermine whether better systems are currently available, and subsequentefforts to associate with such preferred systems. With the acquisitionentry, the access terminal 1220 may limit the search for specific bandand channel. For example, one or more femto channels may be definedwhereby all femto access points (or all restricted femto access points)in a region operate on the femto channel(s). The search for the mostpreferred system may be repeated periodically. Upon discovery of apreferred femto access point 1210, the access terminal 1220 selects thefemto access point 1210 for camping within its coverage area.

A femto access point may be restricted in some aspects. For example, agiven femto access point may only provide certain services to certainaccess terminals. In deployments with so-called restricted (or closed)association, a given access terminal may only be served by the macrocell mobile network and a defined set of femto access points (e.g., thefemto access points 1210 that reside within the corresponding userresidence 1230). In some implementations, an access point may berestricted to not provide, for at least one node, at least one of:signaling, data access, registration, paging, or service.

In some aspects, a restricted femto access point (which may also bereferred to as a Closed Subscriber Group Home NodeB) is one thatprovides service to a restricted provisioned set of access terminals.This set may be temporarily or permanently extended as necessary. Insome aspects, a Closed Subscriber Group (CSG) may be defined as the setof access points (e.g., femto access points) that share a common accesscontrol list of access terminals.

Various relationships may thus exist between a given femto access pointand a given access terminal. For example, from the perspective of anaccess terminal, an open femto access point may refer to a femto accesspoint with no restricted association (e.g., the femto access pointallows access to any access terminal). A restricted femto access pointmay refer to a femto access point that is restricted in some manner(e.g., restricted for association and/or registration). A home femtoaccess point may refer to a femto access point on which the accessterminal is authorized to access and operate on (e.g., permanent accessis provided for a defined set of one or more access terminals). A guestfemto access point may refer to a femto access point on which an accessterminal is temporarily authorized to access or operate on. An alienfemto access point may refer to a femto access point on which the accessterminal is not authorized to access or operate on, except for perhapsemergency situations (e.g., 911 calls).

From a restricted femto access point perspective, a home access terminalmay refer to an access terminal that is authorized to access therestricted femto access point (e.g., the access terminal has permanentaccess to the femto access point). A guest access terminal may refer toan access terminal with temporary access to the restricted femto accesspoint (e.g., limited based on deadline, time of use, bytes, connectioncount, or some other criterion or criteria). An alien access terminalmay refer to an access terminal that does not have permission to accessthe restricted femto access point, except for perhaps emergencysituations, for example, such as 911 calls (e.g., an access terminalthat does not have the credentials or permission to register with therestricted femto access point).

For convenience, the disclosure herein describes various functionalityin the context of a femto access point. It should be appreciated,however, that a pico access point or some other type of node may providethe same or similar functionality for a different (e.g., larger)coverage area. For example, a pico access point may be restricted, ahome pico access point may be defined for a given access terminal, andso on.

The teachings herein may be employed in a wireless multiple-accesscommunication system that simultaneously supports communication formultiple wireless access terminals. Here, each terminal may communicatewith one or more access points via transmissions on the forward andreverse links. The forward link (or downlink) refers to thecommunication link from the access points to the terminals, and thereverse link (or uplink) refers to the communication link from theterminals to the access points. This communication link may beestablished via a single-in-single-out system, amultiple-in-multiple-out (MIMO) system, or some other type of system.

A MIMO system employs multiple (N_(T)) transmit antennas and multiple(N_(R)) receive antennas for data transmission. A MIMO channel formed bythe N_(T) transmit and N_(R) receive antennas may be decomposed intoN_(S) independent channels, which are also referred to as spatialchannels, where N_(S)≦min {N_(T), N_(R)}. Each of the N_(s) independentchannels corresponds to a dimension. The MIMO system may provideimproved performance (e.g., higher throughput and/or greaterreliability) if the additional dimensionalities created by the multipletransmit and receive antennas are utilized.

A MIMO system may support time division duplex (TDD) and frequencydivision duplex (FDD). In a TDD system, the forward and reverse linktransmissions are on the same frequency region so that the reciprocityprinciple allows the estimation of the forward link channel from thereverse link channel. This enables the access point to extract transmitbeam-forming gain on the forward link when multiple antennas areavailable at the access point.

FIG. 14 illustrates a wireless device 1410 (e.g., an access point) and awireless device 1450 (e.g., an access terminal) of a sample MIMO system1400. At the device 1410, traffic data for a number of data streams isprovided from a data source 1412 to a transmit (“TX”) data processor1414. Each data stream may then be transmitted over a respectivetransmit antenna.

The TX data processor 1414 formats, codes, and interleaves the trafficdata for each data stream based on a particular coding scheme selectedfor that data stream to provide coded data. The coded data for each datastream may be multiplexed with pilot data using OFDM techniques. Thepilot data is typically a known data pattern that is processed in aknown manner and may be used at the receiver system to estimate thechannel response. The multiplexed pilot and coded data for each datastream is then modulated (i.e., symbol mapped) based on a particularmodulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for thatdata stream to provide modulation symbols. The data rate, coding, andmodulation for each data stream may be determined by instructionsperformed by a processor 1430. A data memory 1432 may store programcode, data, and other information used by the processor 1430 or othercomponents of the device 1410.

The modulation symbols for all data streams are then provided to a TXMIMO processor 1420, which may further process the modulation symbols(e.g., for OFDM). The TX MIMO processor 1420 then provides N_(T)modulation symbol streams to N_(T) transceivers (“XCVR”) 1422A through1422T. In some aspects, the TX MIMO processor 1420 applies beam-formingweights to the symbols of the data streams and to the antenna from whichthe symbol is being transmitted.

Each transceiver 1422 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. N_(T)modulated signals from transceivers 1422A through 1422T are thentransmitted from N_(T) antennas 1424A through 1424T, respectively.

At the device 1450, the transmitted modulated signals are received byN_(R) antennas 1452A through 1452R and the received signal from eachantenna 1452 is provided to a respective transceiver (“XCVR”) 1454Athrough 1454R. Each transceiver 1454 conditions (e.g., filters,amplifies, and downconverts) a respective received signal, digitizes theconditioned signal to provide samples, and further processes the samplesto provide a corresponding “received” symbol stream.

A receive (“RX”) data processor 1460 then receives and processes theN_(R) received symbol streams from N_(R) transceivers 1454 based on aparticular receiver processing technique to provide N_(T) “detected”symbol streams. The RX data processor 1460 then demodulates,deinterleaves, and decodes each detected symbol stream to recover thetraffic data for the data stream. The processing by the RX dataprocessor 1460 is complementary to that performed by the TX MIMOprocessor 1420 and the TX data processor 1414 at the device 1410.

A processor 1470 periodically determines which pre-coding matrix to use(discussed below). The processor 1470 formulates a reverse link messagecomprising a matrix index portion and a rank value portion. A datamemory 1472 may store program code, data, and other information used bythe processor 1470 or other components of the device 1450.

The reverse link message may comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message is then processed by a TX data processor 1438,which also receives traffic data for a number of data streams from adata source 1436, modulated by a modulator 1480, conditioned by thetransceivers 1454A through 1454R, and transmitted back to the device1410.

At the device 1410, the modulated signals from the device 1450 arereceived by the antennas 1424, conditioned by the transceivers 1422,demodulated by a demodulator (“DEMOD”) 1440, and processed by a RX dataprocessor 1442 to extract the reverse link message transmitted by thedevice 1450. The processor 1430 then determines which pre-coding matrixto use for determining the beam-forming weights then processes theextracted message.

FIG. 14 also illustrates that the communication components may includeone or more components that perform handover control operations astaught herein. For example, a handover control component 1490 maycooperate with the processor 1430 and/or other components of the device1410 to send/receive signals to/from another device (e.g., device 1450)as taught herein. Similarly, a handover control component 1492 maycooperate with the processor 1470 and/or other components of the device1450 to send/receive signals to/from another device (e.g., device 1410).It should be appreciated that for each device 1410 and 1450 thefunctionality of two or more of the described components may be providedby a single component. For example, a single processing component mayprovide the functionality of the handover control component 1490 and theprocessor 1430 and a single processing component may provide thefunctionality of the handover control component 1492 and the processor1470.

The teachings herein may be incorporated into various types ofcommunication systems and/or system components. In some aspects, theteachings herein may be employed in a multiple-access system capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., by specifying one or more of bandwidth, transmitpower, coding, interleaving, and so on). For example, the teachingsherein may be applied to any one or combinations of the followingtechnologies: Code Division Multiple Access (“CDMA”) systems,Multiple-Carrier CDMA (“MCCDMA”), Wideband CDMA (“W-CDMA”), High-SpeedPacket Access (“HSPA,” “HSPA+”) systems, Time Division Multiple Access(“TDMA”) systems, Frequency Division Multiple Access (“FDMA”) systems,Single-Carrier FDMA (“SC-FDMA”) systems, Orthogonal Frequency DivisionMultiple Access (“OFDMA”) systems, or other multiple access techniques.A wireless communication system employing the teachings herein may bedesigned to implement one or more standards, such as IS-95, cdma2000,IS-856, W-CDMA, TDSCDMA, and other standards. A CDMA network mayimplement a radio technology such as Universal Terrestrial Radio Access(“UTRA)”, cdma2000, or some other technology. UTRA includes W-CDMA andLow Chip Rate (“LCR”). The cdma2000 technology covers IS-2000, IS-95 andIS-856 standards. A TDMA network may implement a radio technology suchas Global System for Mobile Communications (“GSM”). An OFDMA network mayimplement a radio technology such as Evolved UTRA (“E-UTRA”), IEEE802.11, IEEE 802.16, IEEE 802.20, Flash-OFDM®, etc. UTRA, E-UTRA, andGSM are part of Universal Mobile Telecommunication System (“UMTS”). Theteachings herein may be implemented in a 3GPP Long Term Evolution(“LTE”) system, an Ultra-Mobile Broadband (“UMB”) system, and othertypes of systems. LTE is a release of UMTS that uses E-UTRA. Althoughcertain aspects of the disclosure may be described using 3GPPterminology, it is to be understood that the teachings herein may beapplied to 3GPP (Re199, Re15, Re16, Re17) technology, as well as 3GPP2(IxRTT, 1xEV-DO Re1O, RevA, RevB) technology and other technologies.

The teachings herein may be incorporated into (e.g., implemented withinor performed by) a variety of apparatuses (e.g., nodes). In someaspects, a node (e.g., a wireless node) implemented in accordance withthe teachings herein may comprise an access point or an access terminal

For example, an access terminal may comprise, be implemented as, orknown as user equipment, a subscriber station, a subscriber unit, amobile station, a mobile, a mobile node, a remote station, a remoteterminal, a user terminal, a user agent, a user device, or some otherterminology. In some implementations an access terminal may comprise acellular telephone, a cordless telephone, a session initiation protocol(“SIP”) phone, a wireless local loop (“WLL”) station, a personal digitalassistant (“PDA”), a handheld device having wireless connectioncapability, or some other suitable processing device connected to awireless modem. Accordingly, one or more aspects taught herein may beincorporated into a phone (e.g., a cellular phone or smart phone), acomputer (e.g., a laptop), a portable communication device, a portablecomputing device (e.g., a personal data assistant), an entertainmentdevice (e.g., a music device, a video device, or a satellite radio), aglobal positioning system device, or any other suitable device that isconfigured to communicate via a wireless medium.

An access point may comprise, be implemented as, or known as a NodeB, aneNodeB, a radio network controller (“RNC”), a base station (“BS”), aradio base station (“RBS”), a base station controller (“BSC”), a basetransceiver station (“BTS”), a transceiver function (“TF”), a radiotransceiver, a radio router, a basic service set (“BSS”), an extendedservice set (“ESS”), a macro cell, a macro node, a Home eNB (“HeNB”), afemto cell, a femto access point, a pico access point, or some othersimilar terminology.

In some aspects a node (e.g., an access point) may comprise an accessnode for a communication system. Such an access node may provide, forexample, connectivity for or to a network (e.g., a wide area networksuch as the Internet or a cellular network) via a wired or wirelesscommunication link to the network. Accordingly, an access node mayenable another node (e.g., an access terminal) to access a network orsome other functionality. In addition, it should be appreciated that oneor both of the nodes may be portable or, in some cases, relativelynon-portable.

Also, it should be appreciated that a wireless node may be capable oftransmitting and/or receiving information in a non-wireless manner(e.g., via a wired connection). Thus, a receiver and a transmitter asdiscussed herein may include appropriate communication interfacecomponents (e.g., electrical or optical interface components) tocommunicate via a non-wireless medium.

A wireless node may communicate via one or more wireless communicationlinks that are based on or otherwise support any suitable wirelesscommunication technology. For example, in some aspects a wireless nodemay associate with a network. In some aspects the network may comprise alocal area network or a wide area network. A wireless device may supportor otherwise use one or more of a variety of wireless communicationtechnologies, protocols, or standards such as those discussed herein(e.g., CDMA, TDMA, OFDM, OFDMA, WiMAX, Wi-Fi, and so on). Similarly, awireless node may support or otherwise use one or more of a variety ofcorresponding modulation or multiplexing schemes. A wireless node maythus include appropriate components (e.g., air interfaces) to establishand communicate via one or more wireless communication links using theabove or other wireless communication technologies. For example, awireless node may comprise a wireless transceiver with associatedtransmitter and receiver components that may include various components(e.g., signal generators and signal processors) that facilitatecommunication over a wireless medium.

The functionality described herein (e.g., with regard to one or more ofthe accompanying figures) may correspond in some aspects to similarlydesignated “means for” functionality in the appended claims. Referringto FIGS. 15-19, apparatuses 1500, 1600, 1700, 1800, and 1900 arerepresented as a series of interrelated functional modules. Here, amessage sending module 1502 may correspond at least in some aspects to,for example, a handover controller as discussed herein. A receivingmodule 1504 may correspond at least in some aspects to, for example, acommunication controller as discussed herein. An access pointidentifying module 1506 may correspond at least in some aspects to, forexample, a handover controller as discussed herein. An access pointselecting module 1508 may correspond at least in some aspects to, forexample, a handover controller as discussed herein. A receiving module1602 may correspond at least in some aspects to, for example, acommunication controller as discussed herein. A monitoring module 1604may correspond at least in some aspects to, for example, a receiver asdiscussed herein. A sending module 1606 may correspond at least in someaspects to, for example, a communication controller as discussed herein.A mapping determining module 1702 may correspond at least in someaspects to, for example, a mapping controller as discussed herein. Aninformation storing module 1704 may correspond at least in some aspectsto, for example, a memory device as discussed herein. A receiving module1706 may correspond at least in some aspects to, for example, acommunication controller as discussed herein. A confusion determiningmodule 1708 may correspond at least in some aspects to, for example, ahandover controller as discussed herein. An information using module1710 may correspond at least in some aspects to, for example, a handovercontroller as discussed herein. A sending module 1712 may correspond atleast in some aspects to, for example, a handover controller asdiscussed herein. An access point identifying module 1714 may correspondat least in some aspects to, for example, a handover controller asdiscussed herein. A receiving module 1802 may correspond at least insome aspects to, for example, a communication controller as discussedherein. An access point identifying module 1804 may correspond at leastin some aspects to, for example, a handover controller as discussedherein. A sending module 1806 may correspond at least in some aspectsto, for example, a handover controller as discussed herein. A confusiondetermining module 1808 may correspond at least in some aspects to, forexample, a handover controller as discussed herein. An information usingmodule 1810 may correspond at least in some aspects to, for example, ahandover controller as discussed herein. A receiving module 1902 maycorrespond at least in some aspects to, for example, a communicationcontroller as discussed herein. An information storing module 1904 maycorrespond at least in some aspects to, for example, a statisticscontroller as discussed herein. An information using module 1906 maycorrespond at least in some aspects to, for example, a handovercontroller as discussed herein. A sending module 1908 may correspond atleast in some aspects to, for example, a handover controller asdiscussed herein. A mapping determining module 1910 may correspond atleast in some aspects to, for example, a handover controller asdiscussed herein. An information use determining module 1912 maycorrespond at least in some aspects to, for example, a handovercontroller as discussed herein.

The functionality of the modules of FIGS. 15-19 may be implemented invarious ways consistent with the teachings herein. In some aspects thefunctionality of these modules may be implemented as one or moreelectrical components. In some aspects the functionality of these blocksmay be implemented as a processing system including one or moreprocessor components. In some aspects the functionality of these modulesmay be implemented using, for example, at least a portion of one or moreintegrated circuits (e.g., an ASIC). As discussed herein, an integratedcircuit may include a processor, software, other related components, orsome combination thereof. The functionality of these modules also may beimplemented in some other manner as taught herein. In some aspects oneor more of any dashed blocks in FIGS. 15-19 are optional.

It should be understood that any reference to an element herein using adesignation such as “first,” “second,” and so forth does not generallylimit the quantity or order of those elements. Rather, thesedesignations may be used herein as a convenient method of distinguishingbetween two or more elements or instances of an element. Thus, areference to first and second elements does not mean that only twoelements may be employed there or that the first element must precedethe second element in some manner. Also, unless stated otherwise a setof elements may comprise one or more elements. In addition, terminologyof the form “at least one of: A, B, or C” used in the description or theclaims means “A or B or C or any combination of these elements.”

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that any of the variousillustrative logical blocks, modules, processors, means, circuits, andalgorithm steps described in connection with the aspects disclosedherein may be implemented as electronic hardware (e.g., a digitalimplementation, an analog implementation, or a combination of the two,which may be designed using source coding or some other technique),various forms of program or design code incorporating instructions(which may be referred to herein, for convenience, as “software” or a“software module”), or combinations of both. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, circuits, and steps have been describedabove generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implementedwithin or performed by an integrated circuit (“IC”), an access terminal,or an access point. The IC may comprise a general purpose processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, electrical components, optical components,mechanical components, or any combination thereof designed to performthe functions described herein, and may execute codes or instructionsthat reside within the IC, outside of the IC, or both. A general purposeprocessor may be a microprocessor, but in the alternative, the processormay be any conventional processor, controller, microcontroller, or statemachine. A processor may also be implemented as a combination ofcomputing devices, e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

It is understood that any specific order or hierarchy of steps in anydisclosed process is an example of a sample approach. Based upon designpreferences, it is understood that the specific order or hierarchy ofsteps in the processes may be rearranged while remaining within thescope of the present disclosure. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

In one or more exemplary embodiments, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another. Astorage media may be any available media that can be accessed by acomputer. By way of example, and not limitation, such computer-readablemedia can comprise RAM, ROM, EEPROM, CD-ROM or other optical diskstorage, magnetic disk storage or other magnetic storage devices, or anyother medium that can be used to carry or store desired program code inthe form of instructions or data structures and that can be accessed bya computer. Also, any connection is properly termed a computer-readablemedium. For example, if the software is transmitted from a website,server, or other remote source using a coaxial cable, fiber optic cable,twisted pair, digital subscriber line (DSL), or wireless technologiessuch as infrared, radio, and microwave, then the coaxial cable, fiberoptic cable, twisted pair, DSL, or wireless technologies such asinfrared, radio, and microwave are included in the definition of medium.Disk and disc, as used herein, includes compact disc (CD), laser disc,optical disc, digital versatile disc (DVD), floppy disk and blu-ray discwhere disks usually reproduce data magnetically, while discs reproducedata optically with lasers. Combinations of the above should also beincluded within the scope of computer-readable media. It should beappreciated that a computer-readable medium may be implemented in anysuitable computer-program product.

The previous description of the disclosed aspects is provided to enableany person skilled in the art to make or use the present disclosure.Various modifications to these aspects will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other aspects without departing from the scope of thedisclosure. Thus, the present disclosure is not intended to be limitedto the aspects shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

1. A method of communication, comprising: determining a mappingassociated with an access terminal, wherein the mapping relates a firstidentifier used by the access terminal to identify a first access pointto a second identifier assigned to the first access point; and storinginformation indicative of the mapping.
 2. The method of claim 1, whereinthe determination of the mapping comprises determining that the accessterminal previously accessed the first access point.
 3. The method ofclaim 1, wherein the determination of the mapping is made upon resolvingconfusion associated with use of the first identifier by the accessterminal.
 4. The method of claim 1, wherein a second access pointreceives the first and second identifiers via a measurement report fromthe access terminal to determine the mapping.
 5. The method of claim 1,wherein: a second access point receives the first identifier from theaccess terminal; and the second access point receives the secondidentifier via a message from the first access point that indicates thatthe access terminal accessed the first access point after a radio linkfailure.
 6. The method of claim 5, wherein the message from the firstaccess point comprises a request for access terminal context informationto be relayed from the second access point to the first access point. 7.The method of claim 1, wherein: the access terminal was previouslyhanded-over to the first access point from a second access point; andthe second access point receives the second identifier via a messagerelating to the handover.
 8. The method of claim 1, further comprising:receiving a measurement report comprising the first identifier from theaccess terminal; determining that there is access point confusionassociated with the first identifier; and using the stored informationto resolve the confusion.
 9. The method of claim 1, further comprising:receiving, at a second access point, a measurement report from theaccess terminal comprising the first identifier; using the storedinformation to determine that the access terminal should be handed-overfrom the second access point to the first access point; and sending amessage to prepare the first access point for handover of the accessterminal
 10. The method of claim 1, further comprising: determininganother mapping associated with the access terminal, wherein the anothermapping relates the first identifier to at least one other identifierassigned to at least one other access point, and wherein the storedinformation is indicative of the another relationship; identifying thefirst access point and the at least one other access point as candidatetarget access points for handover of the access terminal based on thestored information; and sending messages to prepare the first accesspoint and the at least one other access point for handover of the accessterminal.
 11. The method of claim 1, wherein the first identifiercomprises a pilot pseudonoise offset or a physical cell identifier. 12.The method of claim 1, wherein: the first identifier comprises aphysical cell identifier; and the second identifier comprises a globalcell identifier.
 13. The method of claim 1, wherein: the first accesspoint comprises a femto access point; the determination of the mappingis performed at a serving macro access point for the access terminal;and the information is stored at the macro access point.
 14. Anapparatus for communication, comprising: a mapping controller configuredto determine a mapping associated with an access terminal, wherein themapping relates a first identifier used by the access terminal toidentify a first access point to a second identifier assigned to thefirst access point; and a memory device configured to store informationindicative of the mapping.
 15. The apparatus of claim 14, wherein thedetermination of the mapping comprises determining that the accessterminal previously accessed the first access point.
 16. The apparatusof claim 14, wherein the determination of the mapping is made uponresolving confusion associated with use of the first identifier by theaccess terminal.
 17. The apparatus of claim 14, further comprising: acommunication controller configured to receive a measurement reportcomprising the first identifier from the access terminal; and a handovercontroller configured to determine that there is access point confusionassociated with the first identifier, and further configured to use thestored information to resolve the confusion.
 18. The apparatus of claim14, wherein: the first access point comprises a femto access point; thedetermination of the mapping is performed at a serving macro accesspoint for the access terminal; and the information is stored at themacro access point.
 19. An apparatus for communication, comprising:means for determining a mapping associated with an access terminal,wherein the mapping relates a first identifier used by the accessterminal to identify a first access point to a second identifierassigned to the first access point; and means for storing informationindicative of the mapping.
 20. The apparatus of claim 19, wherein thedetermination of the mapping comprises determining that the accessterminal previously accessed the first access point.
 21. The apparatusof claim 19, wherein the determination of the mapping is made uponresolving confusion associated with use of the first identifier by theaccess terminal.
 22. The apparatus of claim 19, further comprising:means for receiving a measurement report comprising the first identifierfrom the access terminal; means for determining that there is accesspoint confusion associated with the first identifier; and means forusing the stored information to resolve the confusion.
 23. The apparatusof claim 19, wherein: the first access point comprises a femto accesspoint; the determination of the mapping is performed at a serving macroaccess point for the access terminal; and the information is stored atthe macro access point.
 24. A computer-program product, comprising:computer-readable medium comprising code for causing a computer to:determine a mapping associated with an access terminal, wherein themapping relates a first identifier used by the access terminal toidentify a first access point to a second identifier assigned to thefirst access point; and store information indicative of the mapping. 25.The computer-program product of claim 24, wherein the determination ofthe mapping comprises determining that the access terminal previouslyaccessed the first access point.
 26. The computer-program product ofclaim 24, wherein the determination of the mapping is made uponresolving confusion associated with use of the first identifier by theaccess terminal.
 27. The computer-program product of claim 24, whereinthe computer-readable medium further comprises code for causing thecomputer to: receive a measurement report comprising the firstidentifier from the access terminal; determine that there is accesspoint confusion associated with the first identifier; and use the storedinformation to resolve the confusion.
 28. The computer-program productof claim 24, wherein: the first access point comprises a femto accesspoint; the determination of the mapping is performed at a serving macroaccess point for the access terminal; and the information is stored atthe macro access point.
 29. A method of communication, comprising:receiving an indication of an access point identifier acquired by anaccess terminal; identifying at least one access point based on theaccess point identifier and stored information that indicates a mappingassociated with the access terminal, wherein the mapping relates theaccess point identifier to the at least one other access point; andsending at least one message to the at least one access point to preparethe at least one access point for handover of the access terminal. 30.The method of claim 29, wherein the stored information indicates thatthe access terminal has previously accessed the at least one accesspoint
 31. The method of claim 29, further comprising: determining thatthere is access point confusion associated with the access pointidentifier; and using the stored information to resolve the confusion.32. The method of claim 29, wherein: the at least one access pointcomprises at least one femto access point; the access point identifieris received at a serving macro access point for the access terminal; andthe information is stored at the macro access point.
 33. The method ofclaim 29, wherein the indication of the access point identifier isreceived at the macro access point via a measurement report sent by theaccess terminal.
 34. The method of claim 29, wherein the access pointidentifier comprises a pilot pseudonoise offset or a physical cellidentifier.
 35. The method of claim 29, wherein: the access pointidentifier comprises a physical cell identifier; and the storedinformation maps the access point identifier to at least one global cellidentifier.
 36. An apparatus for communication, comprising: acommunication controller configured to receive an indication of anaccess point identifier acquired by an access terminal; and a handovercontroller configured to identify at least one access point based on theaccess point identifier and stored information that indicates a mappingassociated with the access terminal, wherein the mapping relates theaccess point identifier to the at least one other access point, whereinthe handover controller is further configured to send at least onemessage to the at least one access point to prepare the at least oneaccess point for handover of the access terminal.
 37. The apparatus ofclaim 36, wherein the stored information indicates that the accessterminal has previously accessed the at least one access point
 38. Theapparatus of claim 36, wherein the handover controller is furtherconfigured to: determine that there is access point confusion associatedwith the access point identifier; and use the stored information toresolve the confusion.
 39. The apparatus of claim 36, wherein: the atleast one access point comprises at least one femto access point; theaccess point identifier is received at a serving macro access point forthe access terminal; and the information is stored at the macro accesspoint.
 40. An apparatus for communication, comprising: means forreceiving an indication of an access point identifier acquired by anaccess terminal; means for identifying at least one access point basedon the access point identifier and stored information that indicates amapping associated with the access terminal, wherein the mapping relatesthe access point identifier to the at least one other access point; andmeans for sending at least one message to the at least one access pointto prepare the at least one access point for handover of the accessterminal.
 41. The apparatus of claim 40, wherein the stored informationindicates that the access terminal has previously accessed the at leastone access point
 42. The apparatus of claim 40, further comprising:means for determining that there is access point confusion associatedwith the access point identifier; and means for using the storedinformation to resolve the confusion.
 43. The apparatus of claim 40,wherein: the at least one access point comprises at least one femtoaccess point; the access point identifier is received at a serving macroaccess point for the access terminal; and the information is stored atthe macro access point.
 44. A computer-program product, comprising:computer-readable medium comprising code for causing a computer to:receive an indication of an access point identifier acquired by anaccess terminal; identify at least one access point based on the accesspoint identifier and stored information that indicates a mappingassociated with the access terminal, wherein the mapping relates theaccess point identifier to the at least one other access point; and sendat least one message to the at least one access point to prepare the atleast one access point for handover of the access terminal.
 45. Thecomputer-program product of claim 44, wherein the stored informationindicates that the access terminal has previously accessed the at leastone access point
 46. The computer-program product of claim 44, whereinthe computer-readable medium further comprises code for causing thecomputer to: determine that there is access point confusion associatedwith the access point identifier; and use the stored information toresolve the confusion.
 47. The computer-program product of claim 44,wherein: the at least one access point comprises at least one femtoaccess point; the access point identifier is received at a serving macroaccess point for the access terminal; and the information is stored atthe macro access point.
 48. A method of communication, comprising:receiving information that indicates that a common identifier is used toidentify a plurality of access points during handovers from a firstaccess point; and providing statistical information indicative of aprobability that a given one of the access points is identified by thenode identifier during a handover from the first access point.
 49. Themethod of claim 48, further comprising: receiving the identifier from anaccess terminal; and using the statistical information to identify, fromthe plurality of access points, at least one candidate target accesspoint for handing-over the access terminal from the first access point.50. The method of claim 49, further comprising sending at least onemessage to prepare the at least one candidate target access point forhandover of the access terminal.
 51. The method of claim 49, wherein theidentification of the at least one candidate target access pointcomprises determining which of the access points is associated with ahighest probability of being identified by the identifier during ahandover.
 52. The method of claim 49, further comprising: determiningwhether a mapping is maintained for the access terminal, wherein themapping maps the identifier to an access point to which the accessterminal was handed-over during a prior handover from the first accesspoint; and determining whether to use the statistical information toidentify the at least one candidate target access point based on thedetermination of whether the mapping is maintained.
 53. The method ofclaim 48, wherein the information is received and the statisticalinformation is stored at the first access point.
 54. The method of claim48, wherein: the identifier comprises a physical cell identifier; andthe received information relates the physical cell identifier to globalcell identifiers assigned to the plurality of access points.
 55. Anapparatus for communication, comprising: a communication controllerconfigured to receive information that indicates that a commonidentifier is used to identify a plurality of access points duringhandovers from a first access point; and a statistics controllerconfigured to provide statistical information indicative of aprobability that a given one of the access points is identified by thenode identifier during a handover from the first access point.
 56. Theapparatus of claim 55, wherein the communication controller is furtherconfigured to receive the identifier from an access terminal, theapparatus further comprising: a handover controller configured to usethe statistical information to identify, from the plurality of accesspoints, at least one candidate target access point for handing-over theaccess terminal from the first access point.
 57. The apparatus of claim56, wherein the identification of the at least one candidate targetaccess point comprises determining which of the access points isassociated with a highest probability of being identified by theidentifier during a handover.
 58. The apparatus of claim 55, wherein theinformation is received and the statistical information is stored at thefirst access point.
 59. An apparatus for communication, comprising:means for receiving information that indicates that a common identifieris used to identify a plurality of access points during handovers from afirst access point; and means for providing statistical informationindicative of a probability that a given one of the access points isidentified by the node identifier during a handover from the firstaccess point.
 60. The apparatus of claim 59, further comprising: meansfor receiving the identifier from an access terminal; and means forusing the statistical information to identify, from the plurality ofaccess points, at least one candidate target access point forhanding-over the access terminal from the first access point.
 61. Theapparatus of claim 60, wherein the identification of the at least onecandidate target access point comprises determining which of the accesspoints is associated with a highest probability of being identified bythe identifier during a handover.
 62. The apparatus of claim 59, whereinthe information is received and the statistical information is stored atthe first access point.
 63. A computer-program product, comprising:computer-readable medium comprising code for causing a computer to:receive information that indicates that a common identifier is used toidentify a plurality of access points during handovers from a firstaccess point; and provide statistical information indicative of aprobability that a given one of the access points is identified by thenode identifier during a handover from the first access point.
 64. Thecomputer-program product of claim 63, wherein the computer-readablemedium further comprises code for causing the computer to: receive theidentifier from an access terminal; and use the statistical informationto identify, from the plurality of access points, at least one candidatetarget access point for handing-over the access terminal from the firstaccess point.
 65. The computer-program product of claim 64, wherein theidentification of the at least one candidate target access pointcomprises determining which of the access points is associated with ahighest probability of being identified by the identifier during ahandover.
 66. The computer-program product of claim 63, wherein theinformation is received and the statistical information is stored at thefirst access point.